Too Few Or Too Many Adult Teeth?

Depending on how many wisdom teeth come in and whether or not they have to be removed, most adults have 28-32 adult teeth.

There are a few outliers in either direction, however. Some people have fewer teeth than they should (called hypodontia or congenitally missing teeth), while others have one or more extra (called hyperdontia or supernumerary teeth). How does this happen and what do we do about it?

Congenitally Missing Teeth

Between 2-4 percent of the population has at least one tooth missing from the adult set. The most common teeth affected by this condition are wisdom teeth, lower second premolars, and upper lateral incisors. It’s not really an issue to be missing wisdom teeth, but missing incisors and premolars can cause difficulties with chewing, the surrounding teeth may shift, and the decreased jaw support can lead to additional tooth loss.

The reason for congenitally missing teeth is nearly always genetics, which is why you tend to see it run in families. Sometimes it happens in conjunction with a larger genetic disorder like Down syndrome or ectodermal dysplasia.

Supernumerary Teeth

At the other end of the dental spectrum is hyperdontia, where extra teeth develop in the jaw. It happens more often with adult teeth than baby teeth. We don’t fully understand what causes this condition, but one leading theory is that it could be the result of a tooth bud dividing abnormally, producing two teeth instead of one.

Supernumerary teeth aren’t always shaped like normal teeth. They can also be peg-shaped, have multiple cusps, or simply be a mass of dental tissue. However they develop, they often don’t have room to erupt, so they remain impacted in the gums, causing crowding and alignment problems for the normal teeth.

Video Transcript

Hyperdontia

Hyperdontia is the condition of having supernumerary teeth, or teeth that appear in addition to the regular number of teeth. They can appear in any area of the dental arch and can affect any dental organ. The opposite of this condition is hypodontia, where there is a congenital lack of teeth. This is seen more commonly than hyperdontia. The scientific definition of hyperdontia is “any tooth or odontogenic structure that is formed from tooth germ in excess of usual number for any given region of the dental arch” They can be a lot of teeth or not many teeth and can occur on any place in the dental arch.

They may be symmetrical or non-symmetrical. Types [^]  Supernumerary teeth can be classified by shape and by position. The shapes include the following: When classified by position, a supernumerary tooth may be referred to as a mesiodens, a paramolar, or a distomolar. Occasionally, these teeth do not erupt into the oral cavity, but manifest as a malocclusion. The most common supernumerary tooth is a mesiodens, which is a malformed, peg-like tooth that occurs between the maxillary central incisors. Fourth and fifth molars that form behind the third molars are another kind of supernumerary teeth.

Prevalence It is evident that hyperdontia Is more common in the permanent dentition than in the primary. The difference between the prevalence of these teeth in permanent dentition in males and females is considerate. Males show hyperdontia twice as often as females. This approximation does vary in terms of location, any other associating syndromes and ethnicity of the individual. In terms of ethnicity it can be seen that hyperdontia is in fact less common in Caucasian than in Asian populations.

There is evidence to show that an individual is more likely to have hyperdontia if people in their family also have hypodontia. Detection of supernumerary teeth Supernumerary teeth may be detected by taking two different x-rays at different angles. Examples of this may be an intra-oral X-ray and a panoramic radiograph. However, these x-rays are 2D and therefore do not accurately portray the 3D view of the teeth. Causes There is evidence of hereditary factors along with some evidence of environmental factors leading to this condition. While a single excess tooth is relatively common,

multiple hyperdontia is rare in people with no other associated diseases or syndromes. Many supernumerary teeth never erupt, but they may delay eruption of nearby teeth or cause other dental or orthodontic problems. Molar-type extra teeth are the rarest form. Dental X-rays are often used to diagnose hyperdontia. It is suggested that supernumerary teeth develop from a third tooth bud arising from the dental lamina near the regular tooth bud or possibly from splitting the regular tooth bud itself.

Supernumerary teeth in deciduous teeth are less common than in permanent teeth. Hyperdontia may be seen in a multitude of syndromic conditions such as: Cleft lip/palate, Craniofacial Dysplasia, Gardner Syndrome and Sturge-Weber Syndrome. Effects The presence of a supernumerary tooth, particularly when seen in young children, is associated with a disturbance of the maxillary incisor region. This commonly results in the impaction of the incisors during the mixed dentition stage. The study debating this also considered many other factors such as: the patient’s age, number, morphology, growth orientation

and position of the supernumerary tooth. Alongside this issue the presence of an extra tooth can impede the eruption of other extra or adjacent normal teeth. Therefore, the presence of a supernumerary tooth when found must be appropriately approached with the correct treatment plan incorporating the likelihood of incisal crowding. In some individuals the eruption of extra teeth can occur far from the dental arch i.e. within the maxillary sinus. Extra teeth may also migrate to a different location after development. In some cases,

extra teeth may cause cysts forming. Crowding is also something frequently seen in people with extra teeth. Removal Although these teeth are usually asymptomatic and pose no threat to the individual, they are often extracted for aesthetic reasons, to allow the eruption of other teeth, orthodontic reasons and/or suspected pathology. This is done particularly if the mesiodens is positioned in the maxillary central incisor region. The traditional method of removal is done by using bone chisels, although a more advanced technique has been found to be more beneficial, especially if surgery is required. Through the use of Piezoelectricity,

Piezoelectric ultrasonic bone surgery may be more time consuming than the traditional method, but it seems to reduce the post-operative bleeding and associated complications quite significantly. WikiVidi.com

Treatment For Hypodontia And Hyperdontia

The typical treatment for extra teeth is to extract them if there isn’t room for them, but dealing with a congenitally missing tooth can be more complicated. Depending on the age of the patient and how long the tooth has been missing, different options may be better. The first step is usually orthodontic treatment so that the gap will be wide enough to fit a replacement tooth. These come in a few forms:

• Removable partial dentures are a simple solution. They can be attached to a retainer or anchored in place by the surrounding teeth.
• Dental bridges “bridge” the gaps by anchoring to the neighboring teeth, but unlike dentures, they’re cemented in place.
• The most permanent solution is a dental implant, which functions like a normal tooth. An implant consists of a post fixed in the jaw bone with a crown on top that matches the natural teeth. Implants can also provide support for bridges when multiple teeth are missing.

Let’s Take A Look At Those Teeth

With regular dental appointments, we can catch cases of hypodontia and hyperdontia early on and make a plan for how to address it. Keep up with your daily dental hygiene routine, keep scheduling those regular appointments, and give us a call if you have any questions about these rare conditions!

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